Electroanalytical application of a boron-doped diamond electrode: Improving the simultaneous voltammetric determination of amlodipine and valsartan in urine and combined dosage forms

• Amlodipine and valsartan are determined simultaneously by voltammetry.
• A cathodically pretreated diamond electrode was used to develop the novel method.
• It can be applied in all the different dosages available in the market.
• The obtained results agree with those of comparative chromatography method.
• The new method was applied in synthetic urine sample with adequate recovery results.

A new voltammetric method was developed for simultaneous determination of amlodipine (AML) and valsartan (VAL) in synthetic urine and combined pharmaceutical formulations. The anodic peak potentials of AML and VAL oxidation at a cathodically pretreated boron-doped diamond electrode were found to be 0.791 V and 1.37 V (vs. Ag/AgCl (3.0 mol L−1 KCl)), respectively, by cyclic voltammetry, in Britton–Robinson buffer solution (pH 5.0). Using square-wave voltammetry, the obtained analytical curves were linear in the AML and VAL concentration range from 0.497–28.0 μmol L−1 and 19.8–280 μmol L−1 with detection limits of 0.0764 μmol L−1 and 0.193 μmol L−1, respectively. The proposed method was successfully applied in the simultaneous determination of AML and VAL in various combined dosage forms available in the market, with results similar to those obtained using a comparative chromatography method. Additionally, adequate recovery results were obtained for the simultaneous determination of AML and VAL in synthetic urine sample. Due to its adequate linearity, the proposed method could be a good alternative for simultaneous determination of AML and VAL in all the different dosages available in the market, even in synthetic urine sample.